I'm trying to determine whether a jq expression refers to no items at all, without collapsing null and empty.
As I understand it, .foo? should be identical to try .foo catch empty. Because catch empty is different from catch null, I would then expect the following to return true with <<<'{}' but false with <<<'{"foo": {"bar": null}}':
$ jq 'isempty(.foo?.bar?)'<<<'{}'false$ jq 'isempty(.foo?.bar?)'<<<'{"foo": {"bar": null}}'false...as the result is identical between both cases, clearly my expectation is incorrect.
The goal is to find something I can use in place of isempty above, where the result will be distinguishable between inputs that do and don't have any value matching the expression, even when the value that exists is false or null, working for arbitrary paths (which may or may not walk arrays, etc).